Date: 26 November 2013
Halo sign in IPA
Copyright: n/a
Notes:
CT scan of a neutropenia patient with leukaemia who has 2 lesions. One, on the right, is nodular, abuts on the pleura and is surrounded by a (grey) low attenuation area, referred to as the “halo” sign. This is virtually only seen in invasive fungal infections of the lung, especially early in the course of the disease, during neutropenia. The other lesion visible on this scan, posteriorly on the left, is also typical of invasive pulmonary aspergillosis in that it is pleura-based and has sharply angulated sides typical of vascular invasion and infarction of small lung segments. There is the suggestion of a “halo” sign anteriorly, but there is less confidence in this appearance (compared with the other) because it is only on one side of the lesion.
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Mr RM is 80 and an ex-coal miner.He developed pneumoconiosis from exposure to coal dust. He also developed rheumatoid arthritis and the combination of this disease and pneumoconiosis is called Caplan’s syndrome.
His chest Xray in early 2015 shows extensive bilateral pulmonary shadowing with solid looking nodules superimposed on abnormal lung fields, contraction of his left lung with an elevated diaphragm and a large left upper lobe aspergilloma, displaying a classic air crescent. His CT scan from mid 2014 demonstrates a large aspergilloma in a cavity on the left, with marked pleural thickening around it, which is partially ‘calcified’ towards its base. Inferiorly on other images,remarkable pleural thickening and fibrotic irregular and spiculated nodules are seen, most partially calcified.
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